Change record status: 
Project: 
Introduced in branch: 
8.8.x
Introduced in version: 
8.8.0
Description: 

Deprecation:
The protected properties \Drupal\jsonapi\ResourceType\ResourceType::$disabledFields and ResourceType::$invertedFieldMapping are deprecated in Drupal 8.8 and will be removed in Drupal 9.

Background:
These protected properties on the internal JSON:API value object, ResourceType, were removed because they are no longer necessary. The ResourceType value object has been refactored to use internal value objects extending Drupal\jsonapi\ResourceType\ResourceTypeField. These new objects carry field aliases and the status of the JSON:API field representation (i.e. enabled/disabled).

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done